Information drives business. Companies today rely to an unprecedented extent on online, frequently accessed, constantly changing data to run their businesses. Online transaction processing (OLTP) systems are an important part of running businesses.
Typical OLTP systems involve processing simple to moderately complex transactions with multiple updates occurring to a database. The performance of the database in an OLTP environment is heavily dependent upon I/O speed and memory configurations of the database application and the file system supporting the database application. There is extensive ongoing development to improve I/O performance and memory subsystem performance.
The Oracle Disk Manager™ (ODM) is an alternative I/O interface which can be used by a database application. It provides improvements over the standard POSIX I/O interface by allowing multiple I/O requests per system call, reducing overhead in managing file descriptors, and improving file management semantics.
However, there are potential performance problems with ODM. For example, ODM provides a direct I/O interface, bypassing a file system cache scheme. Such a direct I/O interface has advantages in that it streamlines certain I/O requests (e.g., by circumventing file locking mechanisms and schemes). However, the prevention of caching by the host file system has performance drawbacks with other types of I/O requests. In this manner, the conventional ODM interface can force an unattractive either/or proposition on database administrators.